Composition for polishing pad and polishing pad using the same

ABSTRACT

An object of the invention is to provide a polishing pad having the excellent slurry retaining properties and the large removal rate and a composition for a polishing pad which can form such the polishing pad. A composition for polishing pad of the invention is comprising a water-insoluble matrix material containing a crosslinked polymer and a water-soluble particle dispersed in the water-insoluble matrix material. The elongation remaining after breaking is 100% or less when a test piece comprising the water-insoluble matrix material is broken at 80° C. according to JIS K 6251. A polishing pad of the invention is that at least a part of the polishing pad comprises the composition for polishing pad.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a composition for a polishingpad and a polishing pad using the same, and this polishing pad can besuitably utilized for polishing the surface of semiconductor wafer andthe like.

[0003] 2. Description of the Related Art

[0004] As a method for polishing which can form the surface having thehigh flatness, an attention has been recently paid to CMP (ChemicalMechanical Polishing). In CMP, polishing is performed by flowing down aslurry which is an aqueous dispersion in which abrasives are dispersedto the surface of a polishing pad from an upper side while sliding apolishing pad and a side to be polished.

[0005] A factor which has a great influence on the productivity in thisCMP is the removal rate and, this removal rate is expected to beimproved remarkably by setting at a greater amount of the retainedslurry than previously used amount.

[0006] Hitherto, in CMP, a polyurethane foam containing fine air bubbleshas been used as a polishing pad, and polishing has been performed byretaining a pore opened on the surface of this resin (hereinafter,referred to as “pore”) .

[0007] However, in the polyurethane foam, it is difficult to control thefoaming freely, and it is extremely difficult to control a size offoamed air bubbles, a foam density, and the like through the foamuniformly. As a result, the quality of a polishing pad comprising apolyurethane foam varies, leading to the cause for the varied removalrate and the procession state.

[0008] As a polishing pad in which controlling of a pore is easier uponthis foaming, there are known soluble materials dispersed in a number ofresins described in Japanese Patent laid-open publication Hei 8-500622,Japanese Patent laid-open publication 2000-34416 and Japanese Patentlaid-open Publication 2000-33552, and the like. Among them, theeffectiveness of a polishing pad containing solubles materials issuggested in Japanese Patent laid-open publication Hei 8-500622 andJapanese Patent laid-open publication 2000-33552. However, a matrixmaterial is not studied when it is actually used as a polishing pad.

[0009] In addition, a component material is studied in Japanese Patentlaid-open publication 2000-34416 and the more stable polishing and animprovement in the removal rate are recognized but a further improvementin the slurry retaining properties and the polishing rate is required.

SUMMARY OF THE INVENTION

[0010] The present invention was done in view of the aforementionedcircumstances, and an object of the present invention is to provide apolishing pad which has the great removal rate due to the excellentslurry retaining properties, and can effectively prevent a decrease inthe retaining properties and the removal rate during polishing and evenafter dressing, and a composition for a polishing pad which can formsuch the polishing pad.

[0011] The present inventors studies in detail the mechanism by whichthe slurry retaining properties and the removal rate are graduallydecreased during polishing, and the mechanism in dressing in which apore is formed (face forming) or updated (face updating) on the surfaceof a polishing pad with a diamond whetstone and the like. As a result,we found that, when shear stress is exerted on the previous polishingpad surface by the polishing, dressing and the like, an elongationproduced on the surface of a matrix material which is a main componentmaterial and, thereafter, the surface is deformed plastically and, thus,a pore is choked. Further, we found that since dusts of not only surfaceof a wafer but also a matrix material itself are produced, these dustsalso choke a pore. That is, we found that a sufficient improvement inthe removal rate can not be effected for these causes and, as a methodfor preventing them, the use of a material having the cross-linkingstructure manifesting the elastic recovery in a matrix material iseffective, which resulted in completion of the present invention.

[0012] The present invention is based on the findings described aboveand can be described as follows.

[0013] 1. A composition for a polishing pad which comprises awater-insoluble matrix material containing a crosslinked polymer and awater-soluble particle dispersed in the water-insoluble matrix material.

[0014] 2. The composition for a polishing pad according to 1 above,wherein the elongation remaining after breaking is 100% or less when atest piece comprising the water-insoluble matrix material is broken at80° C.

[0015] 3. The composition for a polishing pad according to 2 above,wherein said water-insoluble matrix material is modified with at leastone selected from the group consisting of an acid anhydride group, acarboxyl group, a hydroxyl group, an epoxy group and an amino group.

[0016] 4. The composition for a polishing pad according to 3 above,wherein said water-soluble particle is an organic water-soluble particlecomprising at least one selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, and/or an inorganicwater-soluble particle comprising at least one selected from the groupconsisting of potassium acetate, potassium nitrate, potassium carbonate,potassium bicarbonate, potassium chloride, potassium bromide, potassiumphosphate and magnesium nitrate.

[0017] 5. The composition for a polishing pad according to 4 above,wherein the amount of said water-soluble particles is 10 to 90% byvolume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.

[0018] 6. The composition for a polishing pad according to 1 above,wherein at least a part of said crosslinked polymer is a crosslinkedrubber.

[0019] 7. The composition for a polishing pad according to 6 above,wherein at least a part of said crosslinked rubber is crosslinked1,2-polybutadiene.

[0020] 8. The composition for a polishing pad according to 7 above,wherein said water-insoluble matrix material is modified with at leastone selected from the group consisting of an acid anhydride group, acarboxyl group, a hydroxyl group, an epoxy group and an amino group.

[0021] 9. The composition for a polishing pad according to 8 above,wherein said water-soluble particle is an organic water-soluble particlecomprising at least one selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, and/or an inorganicwater-soluble particle comprising of at least one selected from thegroup consisting of potassium acetate, potassium nitrate, potassiumcarbonate, potassium bicarbonate, potassium chloride, potassium bromide,potassium phosphate and magnesium nitrate.

[0022] 10. The composition for a polishing pad according to 9 above,wherein the amount of said water-soluble particles is 10 to 90% byvolume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.

[0023] 11. The composition for a polishing pad according to 1 above,wherein said water-soluble particle is provided with an outer shell forinhibiting moisture absorption in at least a part of the outermost part.

[0024] 12. The composition for a polishing pad according to 11 above,wherein said water-soluble particle is an organic water-soluble particlecomprising of at least one selected from the group consisting ofdextrin, cyclodextrin, mannit, lactose, hydroxypropylcellulose,methylcellulose, starch, protein, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide, water-solublephotosensitive resin, sulfonated polyisoprene and sulfonatedpolyisoprene copolymer, and/or an inorganic water-soluble particlecomprising of at least one selected from the group consisting ofpotassium acetate, potassium nitrate, potassium carbonate, potassiumbicarbonate, potassium chloride, potassium bromide, potassium phosphateand magnesium nitrate.

[0025] 13. The composition for a polishing pad according to 12 above,wherein the amount of said water-soluble particles is 10 to 90% byvolume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.

[0026] 14. A polishing pad characterized in that at least a part of saidpolishing pad comprises the composition of a water-insoluble matrixmaterial containing a crosslinked polymer and a water-soluble particledispersed in the water-insoluble matrix material.

[0027] 15. A polishing pad according to 14 above, wherein the elongationremaining after breaking is 100% or less when a test piece comprisingthe water-insoluble matrix material is broken at 80° C.

[0028] 16. A polishing pad according to 15 above, wherein the Shore Dhardness is 35 or more.

[0029] According to the present invention, there can be obtained acomposition for a polishing pad which can afford a polishing pad inwhich a pore is formed in the better state, a pore is not choked even bydressing, and the slurry retaining properties are better. And also,there can be obtained a composition for a polishing pad in which awater-soluble particle contained in said polishing pad does not absorbmoisture and is not swollen, and which can afford a polishing pad havingthe high hardness. In addition, according to the invention, there can beobtained a polishing pad which can perform polishing at the high removalrate.

DETAILED DESCRIPTION OF THE INVENTION

[0030] A composition for a polishing pad of the present invention ischaracterized in that it contains a water-insoluble matrix materialcontaining a crosslinked polymer and a water-soluble particle dispersedin the water-insoluble matrix material.

[0031] A water-soluble particle is dispersed and contained in the wholeof aforementioned “water-insoluble matrix material” (hereinafter, simplyreferred to as “matrix material”). And, in a polishing pad obtained fromthe present composition for a polishing pad, a pore is formed bydissolving a water-soluble particle present on its most superficiallayer by contacting with water. A pore has the functions of retainingthe slurry and causes the polishing dusts to be transiently retained.The “water-soluble particle” is dissolved or swollen by contacting withthe slurry which is an aqueous dispersion in a polishing pad, and exitsfrom a matrix material. The matrix material may be modified with an acidanhydride group, a carboxyl group, hydroxyl group, an epoxy group, anamino group or the like. This modification can regulate the affinitywith a water-soluble particle and the slurry.

[0032] The “crosslinked polymer” constitutes a matrix material andimparts a matrix material with the elastic recovery by the existence ofthe cross-linking structure. The inclusion of the crosslinked polymercan suppress to a small level a displacement by shear stress exerted ona polishing pad during polishing, and can effectively suppress excessivestretching of a matrix material during polishing and during dressing andconsequent plastic deformation to choke a pore, and fuzz of the surfaceof polishing pad, and the like. Therefore, a pore is effectively formed,a decrease in the slurry retaining during polishing is small, and fuzzis small, leading to no adverse effect on the polishing flatness

[0033] It is preferable that this matrix material has the elongationremaining after breaking (hereinafter, simply referred to as “breakingremaining elongation”) of 100% or smaller when a test piece comprising amatrix material is broken at 80° C. according to JIS K 6251. That is, itis preferable that a total distance between marked lines after breakingis 2-fold or less of a distance between marked lines before breaking. Itis preferable that this breaking remaining elongation is 30% or smaller,(more preferably 10% or smaller, particularly preferably 5% or smaller,usually 0% or more). When the breaking remaining elongation exceeds100%, fine pieces which have been scraped from the polishing pad surfaceor stretched during polishing and during face updating tend to easilychoke a pore, being not preferable.

[0034] The “breaking remaining elongation” is an elongation obtained bysubtracting a distance between marked lines before a test from a totaldistance from a marked line to a broken part of respective test piecesfragmented by breaking when a test piece is broken by a tensile testingmachine at a stretching rate of 500 mm/min. and a test temperature of80° C. using a test piece shape of dumbbell No.3 according to JIS K 6251“Method for Tensile Test of Vulcanized Rubber”. Since the heat isproduced by sliding in the actual polishing, a test was performed at atemperature of 80° C.

[0035] Examples of such the crosslinked polymer include curable resinswhich are crosslinked by using as a part of a monomer a polyfunctionalmonomer such as an urethane resin, an epoxy resin, an acrylic resin, anunsaturated polyester resin, vinyl ester resin, and the like andapplying the external energy such as heat and the like, crosslinkedrubbers obtained by cross-linking-reacting butadiene rubber, 1,2-polybutadiene, isoprene rubber, acrylic rubber,acrylonitrile-butadiene rubber, styrene-butadiene rubber,ethylene-propylene rubber, silicone rubber, fluorine rubber,styrene-isoprene rubber and the like, polymers obtained by cross-linkingpolyethylene, polyvinylidene fluoride, and the like (by a cross-linkingagent, or irradiation with ultraviolet rays or electrons or the like),ionomer and the like. These may be used alone or as a mixture of 2 ormore of them.

[0036] Among them, the use of a crosslinked rubber is preferable becausethe crosslinked rubber is stable to strong acids or strong alkaliscontained in the many slurries and hardly is softened by waterabsorption. An amount of the crosslinked rubber contained in acrosslinked polymer may be selected appropriately, or the entirecrosslinked polymer may be composed of a crosslinked rubber, or thecrosslinked polymer may be a mixture with other aforementionedcrosslinked polymers. Among these crosslinked rubbers, rubberscrosslinked using organic peroxides are preferable. It is preferable touse 1, 2-polybutadiene. 1, 2-polybutadiene is preferable because arubber having the higher hardness is easily obtained as compared withother crosslinked rubbers.

[0037] On the other hand, examples of a water-soluble particle dispersedin a matrix material include not only particles which are completelydissolved in water when contacted with it but also particles whichcontain water or the like and, as a result, are swollen into the geland, whereby, are released from a matrix material. Further, examples ofa water-soluble particle include not only particles which are dissolvedin or swollen with water but also particles which are dissolved orswollen when contacted with an aqueous mixed medium containing analcohol solvent such as methanol or the like.

[0038] Examples of such the water-soluble particle include organicwater-soluble particles and inorganic water-soluble particles. Examplesof the organic water-soluble particle include particles made of dextrin,cyclodextrin, mannit, saccharides (lactose and the like), celluloses(hydroxypropylcelluloses, methylcelluloses, and the like), starch,protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid,polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene, sulfonated polyisoprene copolymer, and the like. Further,examples of the inorganic water-soluble particle include particlesformed of potassium acetate, potassium nitrate, potassium carbonate,potassium bicarbonate, potassium chloride, potassium bromide, potassiumphosphate, magnesium nitrate, and the like. These water-solubleparticles may contain the aforementioned respective materials alone orin combination of 2 or more or them. Moreover, the water-solubleparticle may be one kind of water-soluble particle composed of aprescribed material or 2 or more kinds of water-soluble particlescomposed of different materials.

[0039] In addition, it is preferable that this water-soluble particlehas a particle size of 0.1 to 500 μm (more preferably 0.5 to 100 μm)When a particle size is less than 0.1 μm, since a size of a formed poreis smaller than that of an abrasive used, there is a tendency that apolishing pad which can sufficiently retain the slurry is difficult toobtain. On the other hand, a particle size exceeds 500 mμ, since a sizeof a formed pore is excessive, there is a tendency that the mechanicalstrength and the removal rate of the resulting polishing pad arereduced.

[0040] Moreover, it is preferable that the content of this water-solubleparticle is 10 to 90% by volume (more preferably 15 to 60% by volume,more preferably 20 to 40% by volume) when a sum of a matrix material anda water-soluble particle is regarded as 100% by volume. When the contentof a water-soluble particle is less than 10% by volume, a pore is notsufficiently formed in the resulting polishing pad and there is atendency that the removal rate is reduced. On the other hand, when awater-soluble particle is contained at an amount of over 90% by volume,there is a tendency that a water-soluble particle present in theinterior of the resulting polishing pad can not be sufficientlyprevented from swelling or dissolving and it becomes difficult to retainthe hardness and the mechanical strength of a polishing pad at anappropriate value.

[0041] In addition, it is preferable that a water-soluble particle isdissolved in water only when exposed on the superficial layer in apolishing pad, and, in the interior of a polishing pad, a water-solubleparticle absorbs moisture and is not further swollen. For this reason,it is preferable that a water-soluble particle is provided with an outershell which inhibits moisture absorption in at least a part of theoutermost part. This outer shell may be physically absorbed onto awater-soluble particle, or chemically bound with a water-solubleparticle, or may be contacted with a water-soluble particle by bothphysical absorption and chemical binding. Examples of a material whichforms an outer shell include epoxy resin, polyimide, polyamide,polysilicate, and the like. Even when this outer shell is formed on apart of a water-soluble particle, the aforementioned effects can besufficiently obtained.

[0042] This water-soluble particle has the function of increasing anindentation hardness of a polishing pad (for example, the Shore Dhardness 35 to 100) in a polishing pad in addition to the function offorming a pore. The greater indentation hardness can increase a pressureloaded to the surface of a polishing wafer in a polishing pad. For thisreason, the removal rate can be improved and, at the same time, the highpolishing flatness can be obtained. Therefore, it is particularlypreferable that this water-soluble particle is a solid material whichcan maintain the sufficient indentation hardness in a polishing pad.

[0043] In the invention, in order to control the affinity of a matrixmaterial with a water-soluble particle as well as the dispersibility ofa water-soluble particle in a matrix material, a compatibilizer may beblended therein. Examples of the compatibilizer include block polymersuch as styrene-butadiene-styrene block polymer and the like, randomcopolymer such as styrene-butadiene copolymer, polymer modified with anacid anhydride group, a carboxyl group, a hydroxyl group, an epoxygroup, an oxazoline group, an amino group, and the like, as well asvarious nonionic surface active agent, coupling agent such as silanecoupling agent and the like.

[0044] In addition, a matrix material may contain at least one ofabrasive, oxidizing agent, polyvalent metal ions, hydroxide and acid ofalkali metal, pH adjusting agent, surfactant, scratch preventing agent,and the like which have been previously contained in the slurry inaddition to a water-soluble particle. This makes it possible to performpolishing by supplying only water during polishing when a polishing padformed from this composition for a polishing pad is used.

[0045] The abrasive may be inorganic particles, organic particles andorganic/inorganic composite particles. As inorganic particles there maybe used particles composed of silicon or metal oxides such as silica,alumina, ceria, titania, zirconia, iron oxide, manganese oxide or thelike.

[0046] As organic particles there may be used particles composed ofthermoplastic resins such as (1) polystyrene and styrene-basedcopolymers, (2) (meth)acrylic resins such as polymethyl methacrylate,and acrylic-based copolymers, (3) polyvinyl chloride, polyacetals,saturated polyesters, polyamides, polyimides, polycarbonates and phenoxyresins, and (4) polyolefins such as polyethylene, polypropylene,poly-1-butene, poly-4-methyl-1-pentene, and olefin-based copolymers.

[0047] Also, the organic particles, a polymer with a crosslinkedstructure obtained by copolymerization of styrene, methyl methacrylateor the like with divinylbenzene, ethyleneglycol dimethacrylate or thelike may also be used. The degree of crosslinking can be used to adjustthe hardness of the organic particles.

[0048] There may also be used organic particles composed ofthermosetting resins such as phenol resins, urethane resins, urearesins, melamine resins, epoxy resins, alkyd resins and unsaturatedpolyester resins.

[0049] These inorganic particles and organic particles may be used aloneor in combinations of two or more.

[0050] Organic/inorganic composite particles is not particularlylimited, the organic/inorganic composite particles may have the organicparticles and inorganic particles formed integrally to an extent so asnot to easily separate during the polishing process, and there are noparticular restrictions on their types or structures.

[0051] As composite particles there may be used particles formed bypolycondensation of an alkoxysilane, aluminum alkoxide, titaniumalkoxide or the like in the presence of polymer particles ofpolystyrene, polymethyl methacrylate or the like, and bonding ofpolysiloxane or the like on at least the surface of the polymerparticles. The resulting polycondensate may be directly bonded to thefunctional group of the polymer particles, or it may be bonded via asilane coupling agent or the like.

[0052] The polycondensate does not necessarily need to be chemicallybonded to the polymer particles, and the three-dimensionally formedpolycondensate may by physically held on the surface of the polymerparticles. Silica particles or alumina particles may also be usedinstead of an alkoxysilane. These may also be held by intertwining withthe polysiloxane, or they may be chemically bonded to the polymerparticles by their functional groups, such as hydroxyl groups.

[0053] As examples of specific oxidizing agents there may be mentionedhydrogen peroxide, organic peroxides such as peracetic acid, perbenzoicacid, tert-butylhydroperoxide, and the like, permanganate compounds suchas potassium permanganate, and the like, bichromate compounds such aspotassium bichromate, and the like, halogenate compounds such aspotassium iodate, and the like, nitric compounds such as nitric acid,iron nitrate, and the like, perhalogenate compounds such as perchloricacid, and the like, transition metal salts such as potassiumferricyanide, and the like, persulfuric compounds such as ammoniumpersulfate, and the like, and heteropoly acids. Particularly preferredamong these oxidizing agents are hydrogen peroxide and organic peroxideswhich contain no metals and whose decomposition products are harmless.Including such oxidizing agents can give an even more vastly improvedremoval rate.

[0054] The content of the oxidizing agent may be preferably 0.01 to 20parts, more preferably 0.05 to 20 parts and particularly 0.1 to 5 parts,in 100 parts of the non-water-soluable matrix material. Since sufficientimprovement in the removal rate can be achieved if the oxidizing agentis added at 0.01 parts, there is no need to add it at greater than 20parts.

[0055] As polyvalent metal ions there may be mentioned metal ions suchas aluminum, titanium, vanadium, chromium, manganese, iron, cobalt,nickel, copper, zinc, germanium, zirconium, molybdenum, tin, antimony,tantalum, tungsten, lead and cerium. Any one of these may be used, ortwo or more polyvalent metal ions may be used in combination.

[0056] The polyvalent metal ion content may be up to 3000 ppm, andpreferably from 3 to 3000 ppm, in the aqueous dispersion.

[0057] The polyvalent metal ion may be produced by mixing with theaqueous medium a salt such as a nitric acid salt, sulfuric acid salt oracetic acid salt or a chelate containing a polyvalent metal element, andit may also be produced by mixing an oxide of a polyvalent metalelement. There may also be used a compound that produces a monovalentmetal ion when mixed with the aqueous medium, but whose ion becomes apolyvalent metal ion by the oxidizing agent. Of these various salts andchelates, iron nitrate is preferred because of its particularlyexcellent effect of improving the removal rate.

[0058] As alkali metal hydroxides there may be used sodium hydroxide,potassium hydroxide, rubidium hydroxide, cesium hydroxide and the like.And an acid is not particularly restricted, and any organic acid orinorganic acid may be used. As organic acids there may be mentionedpara-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprenesulfonicacid, gluconic acid, lactic acid, citric acid, tartaric acid, malicacid, glycolic acid, malonic acid, formic acid, oxalic acid, succinicacid, fumaric acid, maleic acid and phthalic acid. These organic acidsmay be used alone or in combinations of two or more. As inorganic acidsthere may be mentioned nitric acid, hydrochloric acid and sulfuric acid,and any one or more of these may be used. An organic acid and aninorganic acid may also be used in combination.

[0059] The contents of these acids may 0.05 to 20 parts, especially 0.1to 15 parts and more preferably 0.3 to 10 parts in 100 parts of thewater-insolublematrix material.

[0060] The pH adjustment may be accomplished with an acid such as nitricacid or sulfuric acid, or with an alkali such as pottasium hydroxide,sodium hydroxide or ammonia. Adjustment of the pH of the aqueousdispersion can increase the removal rate, and the pH is preferablydetermined as appropriate within the range where the abrasive can existstably in consideration of the electrochemical properties of the workingsurface, the dispersability and stability of the polymer particles andthe removal rate.

[0061] As surfactants there may be used cationic surfactants, anionicsurfactants or non-ionic surfactants. As cationic surfactants there maybe mentioned fatty amines, aliphatic ammonium salts and the like. Asanionic surfactants there may be mentioned carboxylic acid salts such asfatty acid soaps and alkylether carboxylic acid salts, sulfonic acidsalts such as alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonicacid salts and α-olefinsulfonic acid salts, sulfuric acid ester saltssuch as higher alcohol sulfuric acid ester salts and alkylether sulfuricacid salts, and phosphoric acid esters such as alkylphosphoric acidesters and the like.

[0062] Particularly preferred as surfactants are non-ionic surfactantsbecause of their notable effect of reducing scratches. As non-ionicsurfactants there may be mentioned ethers such as polyoxyethylene alkylether, ether esters such as polyoxyethylene ethers of glycerin esters,and esters such as polyethylene glycol fatty acid esters, glycerinesters, sorbitan esters and the like.

[0063] The content of the surfactant in the scratch inhibitor comprisinga surfactant may be 0.01 to 10 wt %, preferably 0.03 to 5 wt % and morepreferably 0.05 to 3 wt %, especially for a non-ionic surfactant. If thesurfactant content is less than 0.01 wt %, the generation of scratchesmay not be sufficiently reduced, and if it exceeds 10 wt % there may bea tendency toward lower heat resistance and coloring resistance of theorganic particles.

[0064] As scratch inhibitors there may be used at least one from among(1) biphenol, (2) bipyridyl, (3) 2-vinylpyridine and 4-vinylpyridine,(4) salicylaldoxime, (5) o-phenylenediamine and m-phenylenediamine, (6)catechol, (7) o-aminophenol, (8) thiourea, (9) an N-alkylgroup-containing (meth)acrylamide, (10) an N-aminoalkyl group-containing(meth)acrylamide, (11) a heterocyclic compound with a heteropentacycleand with no aromatic ring forming the skeleton, (12) a heterocycliccompound with a heteropentacycle and with an aromatic ring forming theskeleton, (13) phthalazine, (14) a compound with a heterohexacyclebearing three nitrogen atoms, (15) a surfactant, and a derivative of anyof compounds (1) through (14). As derivatives there may be mentionedthese compounds to which are bonded short-chain alkyl groups of 1 to 3carbons, amino groups, hydroxyl groups, mercapto groups and the like.

[0065] These scratch inhibitors may also comprise any desiredcombinations of two or more from among the compounds of (1) through (14)and their derivatives, and the surfactant of (15).

[0066] As heterocyclic compounds with a heteropentacycle and with anaromatic ring forming the skeleton, there may be mentioned7-hydroxy-5-methyl-1,3,4-triazaindolizine, 3H-1,2,3-triazolo[4,5-b]pyridin-3-ol, 1H-tetrazole-1-acetic acid,1-(2-dimethylaminoethyl)-5-mercaptotetrazole, bismuthiol, 4,5-dicyanoimidazole, adenine, 1-phenyl-5-mercapto-1H-tetrazole,3-mercapto-1,2,4-triazole, 2-amino-4,5-dicyano-1H-imidazole,4-amino-1,2,4-triazole, 5-amino-1H-tetrazole, 2-mercaptothiazoline,guanine, 1-phenyl-5-mercapto-1H-tetrazole,4-amino-3-hydrazino-5-mercapto-1,2,4-triazole,3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-tetrazole and the like.

[0067] As heterocyclic compounds with a heteropentacycle and with anaromatic ring forming the skeleton, there may be mentionedbenzotriazoles such as 5-methyl-1H-benzotriazole, tolyltriazole,benzimidazole, benzofloxane, 2,1,3-benzothiadiazole,2-mercaptobenzothiazole, 2-mercaptobenzothiadiazole,2-mercaptobenzooxazole, 2-aminobenzothiazole, 2-mercaptobenzothiazole,2-amino-6-methylbenzothiazole and the like.

[0068] As compounds with a heterohexacycle bearing three nitrogen atomsthere may be mentioned, melamine, 3-amino-5, 6-dimethyl-1,2,4-triazine,2,4-diamino-6-diallylamino-1,3,5-triazine, benzoguanamine andthiocyanuric acid.

[0069] Among these are preferred 7-hydroxy-5-methyl-1,3,4-triazaindolizine, 3-mercapto-1,2,4-triazole,1-phenyl-5-mercapto-1H-tetrazole and 5-methyl-1H-benzotriazole becauseof their superior effect of reducing scratches, and7-hydroxy-5-methyl-1, 3,4-triazaindolizine is particularly preferredbecause of its notable effect of reducing scratches.

[0070] The content of the scratch inhibitor comprising these compounds(1) through (14) or their derivatives is preferably 0.001 to 5 wt %referably 0.005 to 2 wt % and even more preferably 0.01 to 1 wt %. Ifthe content is less than 0.001 wt % the generation of scratches may notbe sufficiently reduced, and if it exceeds 5 wt % the scratch inhibitormay not dissolve sufficiently and may tend to precipitate.

[0071] Further, various additives such as a filler, a softening agent,an antioxidant, an ultraviolet absorbing agent, an antistatic agent, alubricant, a plasticizer, and the like may be added to the compositionsfor a polishing pad of the present invention, if necessary. Further, thecomposition may be reacted and crosslinked by adding a reactive additivesuch as sulfur, peroxide, and the like. In particular, as a filler,materials which improve the stiffness such as calcium carbonate,magnesium carbonate, talc, clay, and the like, and materials and thelike having the polishing effects such as silica, alumina, ceria,zirconia, titanium oxide, ziriconium oxide, manganese dioxide, manganesetrioxide, barium carbonate, and the like may be used.

[0072] A process for preparing this composition for a polishing pad isnot particularly limited. When the process has a kneading step, kneadingcan be performed by the known kneading machine or the like. Examples ofthe kneading machine include a roll, a kneader, a Banbury mixer, anextruder (single screw, multiple screws) , and the like. The kneadedcomposition for a polishing pad may be processed into the desired shapesuch as sheet, block, film, and the like by performing press molding,extrusion molding, injection molding, and the like. In addition, thiscan be processed into the desired size to obtain a polishing pad.

[0073] In addition, a method for dispersing water-soluble particle in amatrix material is not particularly limited but a matrix material, awater-soluble particle and other additives, and the like may be usuallykneaded for dispersion. In this kneading, a matrix material is kneadedby heating for easy processing and it is preferable that a water-solubleparticle is a solid at a temperature of this time point. When awater-soluble particle is a solid, it becomes easy to disperse awater-soluble particle so that the aforementioned preferable particlesize is manifested, regardless of a magnitude of compatibility with amatrix material. Therefore, it is preferable that a kind of awater-soluble particle is selected depending upon a temperature forprocessing a matrix material used.

[0074] A polishing pad of the present invention is characterized in thatat least a part of it is composed of the composition for a polishingpad.

[0075] It is preferable that the Shore D hardness of the polishing padof the present invention is 35 or more (usually 100 or smaller, morepreferably 50 to 90, more preferably 60 to 85). When this Shore Dhardness is less than 35, there is a tendency that a pressure which canbe applied to a material to be polished during polishing is decreased,and the removal rate is reduced and the polishing flatness becomesinsufficient.

[0076] In addition, it is preferable that a size of a pore is 0.1 to 500μm (more preferably 0.5 to 100 μm). When this pore size is less than 0.1μm, since a size is smaller than a size of an abrasive, there is atendency that it becomes difficult to retain an abrasive sufficiently.On the other hand, when a size of a pore exceeds 500 μm, there is atendency that it becomes difficult to obtain the sufficient strength andindentation hardness.

[0077] In order to improve the dischargeabitliy of the slurry or thelike, a groove or a dot pattern may be formed on the surface (polishingside) of the present polishing pad in the prescribed shape.Alternatively, it is possible to obtain a polishing pad exhibiting amultilayer structure such as a polishing pad in which, for example, asoftener layer is applied to the back (opposite to the polishing side)of this polishing pad. Moreover, the shape of this polishing pad is notparticularly limited but can be appropriately selected from the disc,the belt, the roller shapes, and the like depending upon a polishingapparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0078] The present invention will be specifically explained by way ofExamples.

[0079] Preparation of a composition for a polishing pad and molding of apolishing pad

Example 1

[0080] 100 parts by weight of 1, 2-polybutadiene (manufactured by JSRCo., Ltd., trade name “JSR RB830”) which will be a matrix material bycross-linking later and 100 parts by weight of β-cyclodextrin(manufactured by Yokohamakokusai Biokenkyujo K K., trade name “Dexypearlβ-100”) as a water-soluble particle were kneaded with a kneader heatedat 120° C. Thereafter, 0.3 part by weight of an organic peroxide(manufactured by Nihonyushi Co., Ltd., trade name “Perhexin 25B”) wasadded, further kneaded, and reacted to crosslinking and molded at 190°C. for 10 minutes in a mold to obtain a polishing pad having a diameterof 60 cm and a thickness of 2 mm. A volumetric fraction of awater-soluble particle relative to the whole polishing pad (a volumetricfraction of a water-soluble particle relative to a sum of a matrixmaterial and a water-soluble particle like volumetric fraction of awater-soluble particle relative to a sum of acrosslinked polymer and awatersoluble particle) was about 40%.

Example 2

[0081] 100 parts by weight of 1, 2-polybutadiene (manufactured by “JSRCo., Ltd., JSR RB840”) which will be a matrix material by crosslinkinglater and 230 parts by weight of β-cyclodextrin coated with apolypeptide (manufactured by Yokohamakokusai baiokenkyujo Co., Ltd.,tradename “Dexypearl β-100”) as a water-soluble particle were kneadedwith a kneader heated at 120° C. Thereafter, 0.3 part by weight of anorganic peroxide (manufactured by Nihonyushi Co., Ltd., trade name“Perhexin 25B”) was added, further kneaded, and reacted to crosslink andmolded at 190° C. for 10 minutes in a mold to obtain a polishing padhaving a diameter of 60 cm and a thickness of 2 mm. A volumetricfraction of a water-soluble particle relative to the whole polishing pad(a volumetric fraction of a water-soluble particle relative to a sum ofa matrix material and a water-soluble particle like volumetric fractionof a water-soluble particle relative to a sum of a crosslinked polymerand a water-soluble particle) was about 60%.

Comparative Example 1

[0082] 100 parts by weight of an ethylene-vinyl alcohol copolymer resinwhich is a non-crosslinked thermoplastic resin (manufactured by KurareCo., Ltd., trade name “Evar EP-F101”) and 100 parts by weight ofβ-cyclodextrin (manufactured by Yokohamakokusai biokenkyujo Co., Ltd.,trade name “Dexypearl β-100”) as a water-soluble particle were kneadedwith a kneader heated at 200° C., and heat-pressed to mold at 200° C. toobtain a polishing pad having a diameter of 60 cm and a thickness of 2mm. A volumetric fraction of a water-soluble particle relative to thewhole polishing pad (a volumetric fraction of a water-soluble particlerelative to a sum of a matrix material and a water-soluble particle likevolumetric fraction of a water-soluble particle relative to a sum of acrosslinked polymer and a water-soluble particle) was about 44%.

Comparative Example 2

[0083] 1, 2-polybutadiene and β-cyclodexitrine as in Example 1 werekneaded, and press-molded at 120° C. without cross-linking reaction toobtain a polishing pad having a diameter of 60 cm and a thickness of 2mm. A volumetric fraction of a water-soluble particle relative to thewhole polishing pad (a volumetric fraction of a water-soluble particlerelative to a sum of a matrix material and a water-soluble particle likevolumetric fraction of a water-soluble particle relative to a sum of acrosslinked polymer and a water-soluble particle) was about 40%.

[0084] Polishing assessment of polishing performance

[0085] Respective polishing pads obtained in Examples 1 and 2 andComparative Examples 1 and 2 were mounted on a surface plate of apolishing machine (manufactured by SFT Corp., model “Lapmaster LM-15”),and a silica membrane wafer was polished under the conditions of theflat surface rotation number of 50 rpm and the slurry flow rate of 100cc/min. to assess the difference in the polishing performance of eachpolishing pad and the result thereof are shown Table 1. The removal ratewas obtained by measuring a change in a membrane thickness with anoptical membrane thickness measuring machine.

[0086] Further, the surface of a polishing pad was subjected to dressing(grinding with #400 diamond whetstone for 5 minutes) and, thereafter,the state of a pore on this surface was observed with an electronmicroscope. This result is also shown in Table 1. “O” in Table 1indicates that a better pore can be confirmed and “X” indicates that apart of a pore is choked. TABLE 1 Example Comparative example 1 2 1 2Removal rate (μm/min.) 190 250 60 10 State of a pore ∘ ∘ x x Breakingelongation (%) 100 100 >600 >600 Breaking remaining elongation (%) 0 0510 220

[0087] In order to measure the breaking remaining elongation of matrixmaterials used in Examples 1 and 2 and Comparative Examples 1 and 2,materials from which a water-soluble particle is omitted from respectiveExamples 1 and 2 and Comparative Examples 1 and 2 were kneaded andmolded similarly to make sheets. The sheets were cut into the dumbbellNo.3 test piece shape shown in JIS K 6251 to obtain test pieces.

[0088] These respective test pieces were stretched to break at adistance between marked lines of 20 mm, a stretching rate of 500 mm/min.and a test temperature of 80° C. according to JIS K 6251, and thebreaking remaining elongation was calculated based on the aforementionedstandard. In a test piece which did not break even when stretched to amaximum 600%, the piece was forced to cut at this elongation of 600%,and the breaking remaining elongation was calculated. These breakingremaining elongation are also shown in Table 1.

[0089] From the results of Table 1, in Examples 1 and 2 in which amatrix material is a crosslinked polymer, a pore is formed in the betterstate even after dressing. The breaking remaining elongation of matrixmaterials used in these polishing pads were all 0%, and it can be seenthat no elongation after breaking is perceived. It can be seen that theremoval rate is as high as 190 to 250 μm/min. in such the polishing pad.

[0090] To the contrary, in Comparative Example 1, a non-crosslinkedthermoplastic resin was used as a matrix material. It can be seen thatthis non-crosslinked thermoplastic resin has the very large breakingremaining elongation of 510% and, therefore, ductility. In addition, apart of pore was choked by dressing. Therefore, the removal rate is 60μm/min. being 32% of that in Example 1 and 24% of that in Example 2. Onthe other hand, in Comparative Example 2, since a matrix material usedin Examples 1 and 2 is used as a non-crosslinked material, the samplehas not the elastic recovery. For this reason, the breaking remainingelongation is as large as 220%. In addition, a part of pore was chokedby dressing. Therefore, the removal rate is 10 μm/min., being 5% of thatof Example 1 and 4% of that of Example 2.

What is claimed is:
 1. A composition for a polishing pad which comprisesa water-insoluble matrix material containing a crosslinked polymer and awater-soluble particle dispersed in the water-insoluble matrix material.2. The composition for a polishing pad according to claim 1, wherein theelongation remaining after breaking is 100% or less when a test piececomprising the water-insoluble matrix material is broken at 80° C. 3.The composition for a polishing pad according to claim 2, wherein saidwater-insoluble matrix material is modified with at least one selectedfrom the group consisting of an acid anhydride group, a carboxyl group,a hydroxyl group, an epoxy group and an amino group.
 4. The compositionfor a polishing pad according to claim 3, wherein said water-solubleparticle is an organic water-soluble particle comprising at least oneselected from the group consisting of dextrin, cyclodextrin, mannit,lactose, hydroxypropylcellulose, methylcellulose, starch, protein,polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethyleneoxide, water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer, and/or an inorganic water-solubleparticle comprising at least one selected from the group consisting ofpotassium acetate, potassium nitrate, potassium carbonate, potassiumbicarbonate, potassium chloride, potassium bromide, potassium phosphateand magnesium nitrate.
 5. The composition for a polishing pad accordingto claim 4 , wherein the amount of said water-soluble particles is 10 to90% by volume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles.
 6. Thecomposition for a polishing pad according to claim 1, wherein at least apart of said crosslinked polymer is a crosslinked rubber.
 7. Thecomposition for a polishing pad according to claim 6, wherein at least apart of said crosslinked rubber is crosslinked 1,2-polybutadiene.
 8. Thecomposition for a polishing pad according to claim 7, wherein saidwater-insoluble matrix material is modified with at least one selectedfrom the group consisting of an acid anhydride group, a carboxyl group,a hydroxyl group, an epoxy group and an amino group.
 9. The compositionfor a polishing pad according to claim 8, wherein said water-solubleparticle is an organic water-soluble particle comprising at least oneselected from the group consisting of dextrin, cyclodextrin, mannit,lactose, hydroxypropylcellulose, methylcellulose, starch, protein,polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyethyleneoxide, water-soluble photosensitive resin, sulfonated polyisoprene andsulfonated polyisoprene copolymer, and/or an inorganic water-solubleparticle comprising of at least one selected from the group consistingof potassium acetate, potassium nitrate, potassium carbonate, potassiumbicarbonate, potassium chloride, potassium bromide, potassium phosphateand magnesium nitrate.
 10. The composition for a polishing pad accordingto claim 9, wherein the amount of said water-soluble particles is 10 to90% by volume based on 100% by volume as the total amount of saidwater-insoluble matrix material and said water-soluble particles. 11.The composition for a polishing pad according to claim 1, wherein saidwater-soluble particle is provided with an outer shell for inhibitingmoisture absorption in at least a part of the outermost part.
 12. Thecomposition for a polishing pad according to claim 11, wherein saidwater-soluble particle is an organic water-soluble particle comprisingof at least one selected from the group consisting of dextrin,cyclodextrin, mannit, lactose, hydroxypropylcellulose, methylcellulose,starch, protein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylicacid, polyethylene oxide, water-soluble photosensitive resin, sulfonatedpolyisoprene and sulfonated polyisoprene copolymer, and/or an inorganicwater-soluble particle comprising of at least one selected from thegroup consisting of potassium acetate, potassium nitrate, potassiumcarbonate, potassium bicarbonate, potassium chloride, potassium bromide,potassium phosphate and magnesium nitrate.
 13. The composition for apolishing pad according to claim 12, wherein the amount of saidwater-soluble particles is 10 to 90% by volume based on 100% by volumeas the total amount of said water-insoluble matrix material and saidwater-soluble particles.
 14. A polishing pad characterized in that atleast a part of said polishing pad comprises the composition of awater-insoluble matrix material containing a crosslinked polymer and awater-soluble particle dispersed in the water-insoluble matrix material.15. A polishing pad according to claim 14, wherein the elongationremaining after breaking is 100% or less when a test piece comprisingthe water-insoluble matrix material is broken at 80° C.
 16. A polishingpad according to claim 15, wherein the Shore D hardness is 35 or more.